The present invention relates to a valve device at dispensers which are adapted for dispensing portions of liquid or semi-liquid products, preferably foodstuff, from containers, and which dispensers have vacuum pumps for generating a negative pressure in passage systems through which the products are dispensed from the containers.
Dispensers for dispensing portions of foodstuff, e.g. ketchup, mustard or dressing, are used most intensively a few hours during the day, e.g. at lunch time. This means that the content in the containers from which the foodstuff is dispensed, is normally used up during said hours. The empty containers must then be replaced by full containers, which means that the dispensing must be interrupted for a while, prolonging the time of waiting for the customers. In the above case, you notice when the product in the container is used up, but in other cases you do not notice this and the dispensing goes wrong. Said latter case might occur when dispensing is to be carried through in milkshake machines, dishwashing machines or washing machines.
In U.S. Pat. No. 4,275,823 there is described a valve device which, when dispensing portions of liquid foodstuff, automatically closes a discharge passage when a container connected thereto is empty and opens another discharge passage for a full container connected thereto. At this valve device, the valve body is controlled by a spring, which is disadvantageous inter alia because the spring is difficult to clean.
In U.S. Pat. No. 4,819,693 there is described a valve device for controlling a gas flow. The valve body at this valve device is held in its two different positions by means of an electromagnet. For operating an electromagnet, connection to the electricity supply system is required, which, inter alia, for security reasons is not advisable at dispensing devices for liquid or semi-liquid products such as foodstuff.
The object of the present invention has been to eliminate said problems and this is arrived at by means of a valve device having the characterizing features of subsequent claim 1.
Since the valve device is a permanent magnet device, an appropriate construction from an economic and security point of view is obtained, which is particularly suitable for use in connection with dispensers for liquid or semi-liquid foodstuff.
The invention will be further described below with reference to the accompanying drawings, in which